After 62.0 hours , 1.0 g remains unchanged from a sample of 42k . how much 42k was in the original sample?

The half-life of K-42 is 12.360 hours.

62 hours is just about 5 half-lives, so we'd expect about 1/32 of the original amount to remain after that time. (32 = 2^5)

In fact, it's 12.36 / 62 = 5.016 half-lives.

2^5.016 = 32.36

So if you started with 32.36g in the original sample, it would have decayed down to 1g after 5.016 half-lives.

answer: option (4) is the correct answer.

explanation:

areas which are at low altitudes and near the equator tend to receive direct sunlight from the sun. hence, heat energy or radiations from the sun make these areas warmer and they have warmest water.

whereas areas which are at high altitudes and away from the equator do no receive direct sunlight. hence, no direct contact from the sun makes these regions colder and thus, they have colder water.

thus, we can conclude that the statement areas at low latitudes near the equator have the warmest water because they receive the most direct sunlight best explains the relationship between an area's geography and the temperature of its surface water.

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